(a) Field of the Invention
An area-varying capacitive sensor for a linear encoder method, a self-compensation method of the sensor, and a signal linearization method of the sensor are provided. More particularly, the present invention relates to an area-varying capacitive sensor for a linear encoder method for automatically compensating an offset and a drift and linearizing the signal while additionally disposing an electrode and simply processing a signal without applying a complicated signal process to an area varying capacitive sensor having a periodic electrode, a self-compensation method of the sensor, and a signal linearization method of the sensor.
(b) Description of the Related Art
An output signal that is generated when an area-varying capacitive sensor having a periodic electrode is driven represents a period signal that corresponds to area change. Therefore, a displacement that corresponds to a unit like a period of the electrode can be measured by using an encoder method through a period count of a period signal and an analog signal that corresponds to a small displacement can be obtained by analyzing the signal within a period.
However, a peak and a bottom of the signal are changed in a nonlinear manner because of an edge effect of a parallel plate capacitive sensor. That is, the period signal is not an idealistic triangular wave but a triangular wave with round edges. Nonlinearity is increased by the round edges so it is difficult to calculate the accurate displacement, and the entire signal resolution is deteriorated, which must be solved. Also, the process requires automatically compensating an offset and a drift of the sensor, which has never been realized in a device level by using a simple method.
The above information disclosed in this Background section is only for enhancement of understanding of the background of the invention and therefore it may contain information that does not form the prior art that is already known in this country to a person of ordinary skill in the art.